The role of receptors of the autonomic system in regulation of glycogen synthetase activity in the heart and skeletal muscle in rats.

By determining glycogen synthetase activity, rate of 14C-glucose incorporation and glycogen levels, using pharmacologic agents which act on the alpha, beta M and N receptors, the influence of the autonomic system on synthesis of this polysaccharide in heart and skeletal muscle was analysed. The results indicate that the autonomic system is involved in intracellular autoregulation of glycogen synthetase activity through tissue receptors. Drugs which stimulate the cholinergic system depress this enzyme activity in the heart and skeletal muscle indirectly by releasing endogeneous catecholamines (nicotine-gangliconic effect) and also inhibit utilization of energetic ATP and phosphocreatinine reserves in the heart (muscarinic effect). Stimulation of the alpha-adrenergic receptor enhances glycogen anabolism in both types of muscles depending on the stimulatory influence of nonsterified sugers released in the process of glycogen hydrolysis and depression of cAMP level and presence of glucosteroids. Stimulation of beta-adrenergic receptors induces opposite changes. Analysis of the influence of pharmacologic agents that stimulate and inhibit decomposition and synthesis of glycogen showed that hydrolytic decomposition is probably one of the main processes of intracellular autoregulation of glycogen synthetase activity.